Good Reasonably Priced Seperate Phono Stage??

I have a fairly large selection of albums and devote about 1/2 my listening time to them. I have a couple of mc cartridges (lowest is .5mV) and a few of the earlier Grados. I am no expert in electronics, but it seems that most of the sepereate phono preamps I've seen that go for around $500 or so don't appear to be much better than the phono sections found in reasonably good used full feature preamps, i.e. PS Audio, B&K, Adcom etc. Am I completely off base, or is that generally the case?? If not, what outboard preamps should I be looking at?